1. Technical Field
The present disclosure relates to a semiconductor device, a capacitor unit for a semiconductor device, and a semiconductor package, that are used for an HDMI (registered trademark) device, for example, used in the on-vehicle communication field and the high-speed communication field for portable terminals and the like. The present disclosure also relates to a method of manufacturing a embedded capacitor unit. More specifically, the present disclosure relates to upgrading the characteristics of a semiconductor device for high-speed image communication processing used for a display and the like of high vision (2K) and further for high resolution such as 4 k and 8 k.
2. Description of the Related Art
In a portable terminal, a game machine, a flat television, and the like, high-speed signal processing for high vision and further for 4 k and 8 k is required. In the near future, high speed communication for 2 k and 4 k is also considered to be required in an on-vehicle display. In performing such high-speed signal processing, transmission of a large amount of images at a Gbps level is necessary, and it becomes important to satisfy jitter conditions prescribed in standards.
In order to upgrade such jitter characteristics, it is proposed to incorporate a multilayer ceramic capacitor as a decoupling capacitor, together with a semiconductor chip, into a package. The multilayer ceramic capacitor has an advantage in obtaining large capacitance at low cost. However, in the case of disposing a semiconductor chip and a multilayer ceramic capacitor on the same surface, an electrode area of a multilayer ceramic capacitor needs to be small, and a multilayer ceramic capacitor needs to be mounted for each terminal. However, an area region in which the multilayer ceramic capacitor can be mounted is also limited. Moreover, when a multilayer ceramic capacitor is soldered, it becomes necessary to consider a solder remelting measure in the subsequent reflow process. Further, a multilayer ceramic capacitor needs to be mounted on an outer side of a semiconductor chip, and this mounting also has a problem of increasing a projection area of a semiconductor device.
Against these problems, it is proposed to contain, in a package, a laminated capacitor using a TAB (Tape Automated Bonding). In PTL 2, it is proposed to incorporate, into a package, a capacitor using an insulation film and metal foil, as a decoupling capacitor, on a bottom surface of a semiconductor chip. The proposal will be described in further detail, with reference to FIG. 20.
FIG. 20 is a sectional view of a conventional semiconductor package containing a parallel flat capacitor using an insulation film and metal foil. In FIG. 20, reference numeral 1 denotes a TAB (Tape Automated Bonding). On one surface of TAB 1, semiconductor chip 2 is formed, and on the other surface of TAB 1, metal foil 5 is formed with insulation film 4 interposed between TAB 1 and metal foil 5. Then, TAB 1, insulation film 4, and metal foil 5 form capacitor part 6. Bonding wires 7 electrically connect semiconductor chip 2 with lead frames 8, and other bonding wires 7 electrically connect TAB 1 with lead frames 8.
TAB 1 is a tape-shaped flexible circuit board. The TAB tape has a circuit composed of a copper wire formed by etching, on a film made of polyimide.
However, when capacitor part 6 is formed by using TAB 1, it is difficult to satisfy characteristics required as a decoupling capacitor. One reason is that the use of the TAB tape makes it difficult to perform high-temperature processing at or above 400° C. This is because a polyimide material used for the TAB tape cannot bear 400° C. or above. Further, when the TAB tape is used, a dielectric material used to form capacitor part 6 is limited to processing at less than 400° C. That is, the dielectric material needs to be selected from among dielectric materials that are formed at or below a temperature limit of 300° C. at which the TAB tape can bear. As a result, insulation film 4 that can be formed on the surface of the TAB tape is resin-based and has a low dielectric constant. Consequently, it is difficult in some cases to form a decoupling capacitor having an effect capable of bearing high-speed signal processing, that is, capable of suppressing a variation in a power-supply voltage.
FIG. 21 is a sectional view of a semiconductor package containing a conventional capacitor having a dielectric formed on a lead frame. In FIG. 21, it is proposed to use tantalum oxide (∈; about 20 to 27), BaTiO3 (∈; about 2000), SrTiO3 (∈; 150 to 200), BaSrTiO3 (∈; 200 to 450), PbLaZrTiO3 (∈; 750 to 4000), or the like, for a dielectric, and use 42FN, 50FN, Kovar, or the like, for a lead frame (PTL 2).
Forming a capacitor by using a heat-resistance metallic material in this way, instead of using the TAB, is considered. However, an exemplary component of Kovar contains Ni by 29 weight percent (wt %), Co by 17 wt %, Si by 0.2 wt %, Mn by 0.3 wt %, and Fe by 53.5 wt %, for example. Further, a main component of 42FN (another name, 42Alloy) is 42Ni—Fe (wt %), and a main component of 50FN is 50Ni—Fe(wt %). Even though these metallic materials have excellent heat resistance, the metallic materials have a problem in that when these metallic materials are heat treated at a high temperature of 300° C. or above, 600° C. or above, or 900° C. or above in a condition that the metallic materials are processed in a lead frame shape having a fine pattern, fine portions are easily deformed.
That is, even when a capacitor is tried to be formed on a lead frame-shaped heat-resistant metal plate having a fine pattern, when the metallic materials are heat treated at 300° C. or above, a polyimide reinforcing member provided to prevent a dimensional change of a fine portion disappears in the middle of the heating. As described above, the polyimide reinforcing member provided to maintain high precision of a lead-frame end shape part disappears when the polyimide reinforcing member is heat treated at high temperature of 300° C. or above or at 400° C. or above. As a result, dimensional accuracy of the lead frame becomes low.